When applying a coating composition (e.g. paint) to particular structures such as window and picture frames, door panels and lintels, it is often desirable to prevent the coating from contacting areas adjacent to the structure. Painters will often outline the structure with masking tape or another protective coating so that minor inaccuracies in their brush strokes or spraying are prevented from reaching the underlying surface. This outlining process is obviously time-consuming. Furthermore, the removal of the protective tape or coating can leave behind remnants of adhesive on the surface.
As a consequence of these problems, a plethora of paint guides and masking devices have been developed. Such devices are described in UK Patent No. 2,098,688, Japanese Laid-Open Publication No. JP-60-241962 and U.S. Pat. Nos. 4,296,317 and 4,383,496.
U.S. Pat. No. 4,383,496 (Shotwell) discloses a device for painting a window frame together with a tiny perimeter of glass adjacent to the frame. The painted glass perimeter acts to supplement the weatherproofing of the window. The device comprises a frame having a central body portion which is connected at its distal ends via two brackets to a pair of supporting arms, each arm comprising a forward end, a vertical wall and a bottom flange into which are impressed two feet. The central body portion has a flat top from which extend front and rear flanges. The front flange is further extended through the attachment a spring-biased shield which is configured to terminate in a straight edge which extends longitudinally throughout the length of the shield.
In use, the device of U.S. Pat. No. 4,383,496 is placed on a glass surface that is terminated by a frame edge such that the forward end of the arms abuts that frame edge. A small downward pressure applied to the device overcomes the spring-bias of the shield and moves its straight edge into contact with the glass surface. This exposes a thin strip of window glass that is constrained between the frame edge, the two distal arms of the device and the sealing edge. While this pressure is being applied, that portion of the window frame adjacent the device may be painted along with the thin strip. When this pressure is removed, the edge no longer acts as a seal onto the glass. However, at this point the device may be slid along the frame edge using the feet of the arms. A new, discrete section of the frame and a new, discrete strip of window glass may then be painted by repeating the application of pressure.
As a consequence of its configuration, the device of U.S. Pat. No. 4,383,496 does not enable the continuous delivery of paint to the frame or glass perimeter. It is furthermore reliant on the surface being painted having a frame edge of a certain height and integrity.
UK Patent No. 2,089,688 (Daniel) discloses a paint applicator in the form of a spray gun to which is attached a guide. As shown in the FIGS. 1 and 2 of this document, the guide comprises two parallel side edges which extend forward from their point of attachment at the spray gun to two leading edges. In use, the spraying tip of the gun is adjusted such that the spray is released within the bounds of the two parallel, extending side edges. The leading edges are brought into the position wherein they abut a protruding feature, such as a trim edge, along which the paint is to be applied. The applicator must then be moved carefully to maintain the contact between the leading edges and the protrusion.
U.S. Pat. No. 4,296,317 (Kraus) discloses a paint application machine comprising a spray gun controlled by light intensity and electrical pulses, a spray gun guide device and a spray control unit operating in dependence on the position of the spray gun guide device. The guide device essentially consists of two parts. The first part comprises a telescopic arm at the end of which the spray gun is mounted. The telescopic arm is generally held horizontally and, when the machine is moved along a defined line, it is prevented from vibrational shifting off that line. The second part of the guide device comprises a spacing wheel located on the gun housing just underneath the paint exit opening. The wheel ensures the spray gun is maintained at a uniform distance from the working surface.
Japanese Laid-Open Publication No. JP-60-241962 describes a device for applying a coated film of uniform width on or adjacent to, in particular, a window. Paint, provided in a vessel is forced through a pipe into a brushing means that comprises an outlet tip. This brushing means is provided with a bracket which appears to act as a guiding means.